Memory solutions from EXASCEND +++ High-speed and ultra-low-power 8-bit MCU with up to 50 MHz +++ Real Time Clocks - precise billing of charging stations

Precise billing of charging stations with MICRO CRYSTAL Real Time Clocks (RTC)

Real Time Clocks (RTC) from MICRO CRYSTAL

Saves power and provides stable and accurate timing for EV charging stations.

An EVSE charging station (wallbox) that is not permanently connected to a data network needs very accurate RTCs for precise synchronisation of electricity tariffs. These RTCs are also necessary for reliable time recording if the power supply has been down for a long time or the GSM network is on strike.

Time-dependent, inexpensive charging
In order to charge e-vehicles inexpensively at home, it is important to use low-cost electricity tariffs during off-peak periods through time-of-use (TOU) or time-dependent tariffs. (TOU) is a method of measuring and billing energy consumption based on when the energy is used. Utilities charge more when electricity is drawn at peak times of the day.

Time-dependently adjust the available charging current to the different peak / off-peak electricity tariffs. Use the RTCs to control the charging power. For example, you can charge at a higher charging power during the cheaper secondary tariff than at the more expensive main tariff.

Reliable data in real time
With an RTC from MICRO CRYSTAL, the smart meter in the EVSE is always synchronised. The MCU uses reliable real-time data. These enable smart operation based on programmed charge settings (TOU, off-peak times). Edge computing is supported with reliable data from the node for smart grid companies and users.

Additional features such as an integrated 12-bit temperature sensor enables thermal monitoring of EVSE, alarming and extremely high accuracy through temporal temperature compensation. Clock crystals are relatively inaccurate for applications without network connections and must be frequently readjusted.

MICRO CRYSTAL offers RTCs in 3 variants here:

Article name Interface Features



800nA, Extended temperature (-40 to +125°C), +/- 8 ppm



800nA, Extended temperature (-40 to +125°C), +/- 8 ppm



45nA, Standard temperature (-40 to +85°C), +/- 1 ppm bei 25°C


  • High precision time
    -40 to +125°C: +/- 8 ppm or 25°C : +/- 1ppm
  • Extended battery life
    800 nA / 45 nA at 3 V and 25°C in battery backup mode
  • Smart Power Management
    Automatic switching to back-up capacitor / battery / button cell
  • Tamper detection
    External interrupt with time stamp (RV-3028)
  • Ultra-compact housing
    3.7 x 2.5 x 0.9 mm / 3.2 x 1.5 x 0.8 mm ceramic housing with reliable vacuum seal
  • Connection for current measurement
  • Connection for buffering for capacitor, battery or accumulator.
  • All pins accessible
Development Board

With this software (only for the RV-3028) all functions of this RTC can be tested and programmed. The USB-I2C interface from ELV can be used as hardware, which is connected to the development board.

We will gladly send you the software.

Development Software

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